Problem: Simplify the following expression: $z = \dfrac{3t}{10} + \dfrac{t}{8}$
Answer: In order to add expressions, they must have a common denominator. The smallest common denominator is the least common multiple of $10$ and $8$ $\lcm(10, 8) = 40$ $ z = \dfrac{4}{4} \cdot \dfrac{3t}{10} + \dfrac{5}{5} \cdot \dfrac{t}{8} $ $z = \dfrac{12t}{40} + \dfrac{5t}{40}$ $z = \dfrac{12t +5t}{40}$ $z = \dfrac{17t}{40}$